Irrigation towers utilized in irrigating cultivated land are usually provided with support and drive wheels capable of slowly advancing the tower over the land to be irrigated. Inasmuch as the tower wheels are driven very slowly various operating problems are encountered. One problem stems from the tendency of the necessary numerically high ratio drive train for the wheels tending to drive the wheels with surges in driving torque. Another problem is encountered when a tower is moving down an incline and the tower drive mechanism tends to be driven by the tower. In addition, other problems of operation are encountered specific to the various different drive mechanisms heretofore utilized.
Various forms of irrigation tower drive mechanisms including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 2,054,554, 3,771,719, 3,831,692 and Re. 28,728.